Methods and apparatus for embedding images into articles of utility have a long history of development as artisans and craftsmen over the years have continually attempted to introduce visual excitement and interest into articles of a more or less utilitarian nature. These efforts persist because they lend a desirable and pleasant richness to everyday articles. Flexible articles in thin sheet form have especially been the subject of these image-embedding efforts, due to their being an ideal medium into which to incorporate images. This follows naturally as images also are frequently rendered on flexible substrates. Clothing and wall hangings are among the oldest and most common examples of combining images with or into sheets. Upon development later of transparent and translucent materials in sheet form, the creation of an entirely new form of image/web combining evolved. In general, this new form centered around sandwiching images of all types between one or more transparent outer layers for a wide range of purposes beyond the basic purpose of adding a pleasing or aesthetic appearance to an otherwise plain article. Typical secondary purposes have included a desire to protect the images from physical wear and tear, and to prevent destruction of the image medium itself from exposure to water or high moisture.
Descriptions of typical prior art approaches to embedding images into flexible sheets or webs may be found in a number of U.S. patents. Illustrative early teachings that have incorporated simple designs and text messages into translucent materials may be found in U.S. Pat. Nos. 467,567 to Michel and U.S. Pat. No. 2,240,072 to Hodgdon et al. In the 1892 '567 patent, a window shade is described that includes an inner opaque pattern (stylized flowers and straight-lined borders) sandwiched between a top translucent coating and a translucent sized body, so that the pattern is exposed only when the shade is held against light. In the 1941 '072 patent, a pair of transparent outer layers sandwich between them a layer of adhesive that is not as transparent as the outer layers. When the adhesive is still soft, images are physically impressed upon it to produce varying thicknesses. These varying adhesive thicknesses produce variable transparency such that the simple designs and letters become visible when the material is held to a light.
U.S. Pat. No. 1,975,579 to Kernes also provides an early (1934) teaching of a multiple-layered material that may contain pictures, designs, illustrations, and prints interposed between the tissue paper layers forming the overall composite material.
U.S. Pat. No. 5,545,446 to Looi et al. provides a teaching illustrative of a large body of art wherein transparent or translucent layers are formed over inner layers that bear various graphical indicia, generally for the purpose of providing physical or waterproofing protection to the image while providing a pleasing-appearing article formed from the composite, which is visible apparently regardless of the ambient lighting conditions.
While each of these prior art approaches teaches one or another aspect of producing and using flexible sheets having designs and graphical indicia of simple sorts associated with translucent image production, none approaches the unique and elegant capabilities that the present invention admirably provides. Therefore, the image bearing composite optical material as taught in the present invention provides a significantly improved structural and functional capability in this area while retaining all of the desirable high resolution optical properties and simple-to-use attributes.